Five-year persistence of statins after acute myocardial infarction in statin-naive patients

Introduction: Statins play a prominent role in the secondary prevention of cardiovascular disease. Following acute myocardial infarction, statin therapy is a key component of "evidence based" drug therapy. Objective: The authors' aim was to investigate the five-year persistence of statin therapy and to compare the therapeutic efficacy of the individual agents following acute myocardial infarction. Method: The authors first selected patients from the Hungarian National Health Insurance Fund database who presented with acute myocardial infarction ICD (International Classification of Diseases) codes between 01/01/2009 and 31/12/2009. Patients who had any statin drug prescription filled during this period and had no statin prescription filled in the year prior to selection were included. Each patient's statin prescription fill was followed for 5 years, tolerating a 60-day grace period. Patients who died during the study period were excluded from the study. To model persistence, the classical survival analysis toolkit was used, where the "survival" time was the time until drug discontinuation. Results: 6,192 patients met the inclusion criteria. The persistence rate had fallen with rosuvastatin to 24.40%, with fluvastatin to 16.79%, to atorvastatin 15.47%, and with simvastatin to 11.46% after five years. The five-year persistence of statins - allowing for the switch between individual agents - was 30.48%. Compared to rosuvastatin, the risk of discontinuing atorvastatin increased by 37% points (HR = 1.37, 95% CI: 1.29-1.46 p < 0.001), that of fluvastatin by 65% points (HR = 1.65, 95% CI: 1.47-1.85, p < 0.001), while that of simvastatin by 66% points (HR = 1.66, 95% CI: 1.36-2.00, p < 0.001). The average duration of medication, limited to 60 days, was 9.4 months for simvastatin, 18.5 months for fluvastatin, 22.3 months for atorvastatin, and 28.4 months for rosuvastatin. Conclusion: The authors examined the five-year statin persistence of patients who suffered from an acute myocardial infarction. They have found that the adherence to statin therapy significantly decreased after such a period of time, and that there were significant differences between the individual statin agents. Rosuvastatin had the highest five-year persistence.